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-rw-r--r--libdimension/color.c14
1 files changed, 10 insertions, 4 deletions
diff --git a/libdimension/color.c b/libdimension/color.c
index abda9bb..6555578 100644
--- a/libdimension/color.c
+++ b/libdimension/color.c
@@ -298,6 +298,14 @@ dmnsn_sRGB_from_color(dmnsn_color color)
return sRGB;
}
+static double
+dmnsn_color_intensity(dmnsn_color color)
+{
+ dmnsn_sRGB sRGB = dmnsn_sRGB_from_color(color);
+ return 0.2126198631048975*sRGB.R + 0.7151387878413206*sRGB.G
+ + 0.0721499433963131*sRGB.B;
+}
+
/* Add two colors */
dmnsn_color
dmnsn_color_add(dmnsn_color c1, dmnsn_color c2)
@@ -314,10 +322,8 @@ dmnsn_color_add(dmnsn_color c1, dmnsn_color c2)
dmnsn_color ret = dmnsn_color_from_sRGB(sRGB);
/* Weighted average of transparencies by intensity */
- dmnsn_CIE_Lab Lab1 = dmnsn_Lab_from_color(c1, dmnsn_whitepoint);
- dmnsn_CIE_Lab Lab2 = dmnsn_Lab_from_color(c2, dmnsn_whitepoint);
- double L1 = Lab1.L*(1.0 - c1.filter - c1.trans);
- double L2 = Lab2.L*(1.0 - c2.filter - c2.trans);
+ double L1 = dmnsn_color_intensity(c1)*(1.0 - c1.filter - c1.trans);
+ double L2 = dmnsn_color_intensity(c2)*(1.0 - c2.filter - c2.trans);
if (L1 + L2) {
ret.filter = (L1*c1.filter + L2*c2.filter)/(L1 + L2);
ret.trans = (L1*c1.trans + L2*c2.trans) /(L1 + L2);